多信道无线Mesh网络路由机制

在无线Mesh网络中,采用合理设计路由度量来优化网络性能是一种常用的方法.本文对已有的典型路由度量进行分析讨论,比较全面的给出了设计无线Mesh网路路由度量应该考虑的重要因素.基于多信道无线Mesh网络的特点,本文提出一个多信道无线Mesh网络路由度量CLIDH,并在此基础上提出一个跨层多信道路由协议CMAODV.仿真结果表明,和已有的路由度量相比较,CLIDH能够充分利用网络资源,使网络性能得到明显改善.     

无线Mesh网络路由协议的研究进展

在简要介绍无线Mesh网络特性的基础之上,对路由协议中若干关键技术的研究状况进行了总结和综述,重点讨论面向无线Mesh网络的路由度量的设计思路、多信道多无线接口环境下节点的自适应信道分配策略以及结合无线介质的广播特性的寻路算法的分析.详细讨论了上述因素对于路由协议性能的具体影响,深入分析了当前研究的优缺点.同时,鉴于无线链路上传输的不可靠和高误码率,详细介绍了跨层协议设计的相关内容.     

无线Mesh网中编码感知组播路由协议CAMR

网络编码是一种能够提高网络吞吐量的新技术,将网络编码应用于无线Mesh网组播对Mesh网络进一步实用化有重要意义.编码感知路由是一种能够充分识别和利用网络中的编码机会的路由.虽然已有若干个基于网络编码的单播路由协议,但无线网络中编码机会并没有被充分利用,到目前为止还没有无线Mesh网络中的编码感知组播路由协议.提出一个编码感知组播路由协议CAMR(coding-aware multicast routing).CAMR协议利用了一个新奇的编码感知路由度量CAM(coding-awarerouting metric),可以度量无线Mesh网络中节点的实际编码机会和编码能力的大小.基于CAM设计的CAMR协议可以充分利用无线Mesh网络中节点的编码机会,提高了无线Mesh网络组播的吞吐量.模拟实验验证了CAMR协议的优势及其有效性.     

无线Mesh网络联合信道分配和路由协议研究

设计合理的联合信道分配和路由协议对多信道无线Mesh网络的性能至关重要。在分析多网卡多信道无线Mesh网络中联合信道分配和路由协议特点和研究现状的基础上,提出了一种与按需路由协议结合的联合信道分配算法,通过选择最小干扰信道来优化信道分配;同时采用了一种适应多信道多网卡网络的路由判据方法,该方法考虑了信道干扰、接口切换以及路径跳数三个关键因素。仿真结果表明,文中所采用的协议能较为明显地提高网络吞吐量及减小分组的端到端时延。     

改进的无线Mesh网路由判据算法及其路由协议

为了改善802.11s无线Mesh网传输过程中因重传次数过大而造成的丢包问题,根据实际无线传输中的网络重传次数特性,提出一种基于最大重传次数的空中传播时间改进路由判据算法.同时为了缓解因单根节点造成的网络拥塞,提高实际场景中边缘节点的传输性能,并保证网络中所有节点使用无线信道资源的公平性,基于树的寻径机制从拓扑结构的角度,提出一种改进的多根节点的混合无线Mesh网路由协议(M-HWMP).理论及仿真结果表明,改进的路由判据算法及路由协议优化了无线Mesh网传输不同数据流时的吞吐量、时延特性,并在一定程度上避免了网络拥塞.     

基于忙音多址的多信道无线Mesh网的MAC协议

无线Mesh网(WMN)是一种新犁宽带无线接入技术,选择适当的MAC子层规范,根据网络业务特征有效地配置信道资源,可以提高Mesh网的无线资源使用效率以及系统传输性能.而现有的无线Mesh网络基本上是采用单信道MAC协议,不能满足日益俱增的用户需求,限制了整个网络的数据传输速率与网络容量.文中基于忙音多址访问的设计思想,结合无线Mesh网络的特点,提出了一种无线Mesh网MAC协议MCBTMA(Multi-Channel Busy Tone Multiple Access).MCBTMA通过构建多个忙信号控制信道和多个数据信道,在MAC层进行多信道调度,使无线Mesh网络在吞吐量和时延方面性能有显著提高.     

面向编码机会路由的无线Mesh 网络广播信道接入

编码机会路由是有损无线Mesh网络中提供高吞吐量和高可靠性传输的理想方案.该路由机制建立在无线广播的多用户分集优势和随机网络编码的纠删特性之上,为广播MAC的设计引入了新的机会和挑战.基于最优停止理论,研究面向编码机会路由的机会广播信道接入问题,提出一种在接入延迟和信道交付能力之间加以折衷,以获得最优的平均有效速率的方法,并在IEEE 802.11 DCF协议基础上设计实现面向NCOR的广播MAC协议O-BCast.仿真结果表明,该协议显著提高了编码机会路由的端到端吞吐量,具有网络负载自适应的良好特性.     

基于忙音多址的多信道无线Mesh网的MAC协议

无线Mesh网（WMN）是一种新型宽带无线接入技术,选择适当的MAC子层规范,根据网络业务特征有效地配置信道资源,可以提高Mesh网的无线资源使用效率以及系统传输性能。而现有的无线Mesh网络基本上是采用单信道MAC协议,不能满足日益俱增的用户需求,限制了整个网络的数据传输速率与网络容量。文中基于忙音多址访问的设计思想,结合无线Mesh网络的特点,提出了一种无线Mesh网MAC协议MCBTMA（Multi-Channel Busy Tone Multiple Access）。MCBTMA通过构建多个忙信号控制信道和多个数据信道,在MAC层进行多信道调度,使无线Mesh网络在吞吐量和时延方面性能有显著提高。     

基于树形拓扑的无线Mesh网络路由协议研究

研究和分析了无线Mesh网络路由协议及其特点,提出了无线Mesh网络路由协议设计原则.遵循这些原则,充分利用Mesh网络全相连的优点构建出树形逻辑拓扑结构,该拓扑结构能满足无线Mesh网络业务特点的要求.在该拓扑树基础上设计了一种基于树形拓扑的无线Mesh网络路由协议(TTRP),该协议采用无开销的源地址学习方式构建路由相关表项,快速链路切换和路由重定向机制大大提高了TTRP路由协议的健壮性和网络的抗毁性.网络仿真结果表明了该路由协议的可行性.     

移动Ad hoc网络组播路由协议研究

移动Ad hoc网络是由一组移动终端组成的无线多跳自治系统,在军事、灾难救助、临时会议等场合应用.多数应用需要提供面向组的服务,因此Ad hoc网络环境下的组播路由协议研究成为当前的一个热点,首先分析比较了多种典型的Ad hoc组播路由协议,最后对Ad hoc组播路由协议做了总结和展望.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

法律信息库系统

本文分析了法律数据库的结构和特点，介绍了采用面向对象设计方法和超文本数据库技术开发和实现法律信息库系统将作为重要网络资源之一为不同用户进行法律咨询服务。     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

International Journal of Automation and Computing Table of Contents

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Information for authors

正SCIENCE CHINA Information Sciences(Sci China Inf Sci),cosponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China,and published by Science China Press,is committed to publishing highquality,original results of both basic and applied research in all areas of information sciences,including computer science and technology;systems science,control science and engineering(published in Issues with odd numbers);information and communication engineering;electronic science and technology(published in Issues with even numbers).Sci China Inf Sci is published monthly in both print and electronic forms.It is indexed by Academic OneFile,Astrophysics Data System(ADS),CSA,Cabells,Current Contents/Engineering,Computing and Technology,DBLP,Digital Mathematics Registry,Earthquake Engineering Abstracts,Engineering Index,Engineered Materials Abstracts,Gale,Google,INSPEC,Journal Citation Reports/Science Edition,Mathematical Reviews,OCLC,ProQuest,SCOPUS,Science Citation Index Expanded,Summon by Serial Solutions,VINITI,Zentralblatt MATH.     

Erratum to: Fast global kernel fuzzy c-means clustering algorithm for consonant/vowel segmentation of speech signal

正Erratum to:J Zhejiang Univ-Sci C(ComputElectron)2014 15(7):551-563doi:10.1631/jzus.C1300320The original version of this article unfortunately contained mistakes.Algorithm 6 should be as follows:Algorithm 6 FGKFCM-F clustering Input:(1)X={x_1,x_2,…,x_N},,x_iR~d,i=1,2,…,N,the dataset;(2)C,1C≤N,the number of clusters;(3)ε0,the stopping criterion;     

Journal of Zhejiang University-SCIENCE C (Computers & Electronics) Total contents

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A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.